Rule engines are computer programs that are used to provide information given an input. The input is processed by one or more rules. Many rule engines require crisp rules in which preconditions consist of crisp tests, for example, dog.age>8 years. The use of such crisp rules may limit the applicability of the rule engines to situations where the logic involve fuzzy concepts such as the dog is old. Modification of a rule engine to support fuzzy rules can be very complex and error prone.